Numereical Microstructure Optimisation of Melt-Infiltrated Metal-Ceramics Composites

• Applicants: Professorin Dr. Romana Piat; Professor Dr.-Ing. Kay A. Weidenmann
• Subject Area: Mechanics ; Materials in Sintering Processes and Generative Manufacturing Processes
• Term: from 2009 to 2015
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 148092144

Melt-infiltrated metal/ceramic composites with lamellar microstructure are materials in the de-velopment stage and show strong dependence of their macroscopic thermo-mechanical properties on the orientation distribution of the lamellar domains.The creation of a virtual model of their microstructure and, consequently, their application for performing microstructural optimization will support the well-directed production of these materials. The microstructure modeling and numerical optimization make it possible to reproduce numerically the behavior of the composite for different combinations of the design variables and, thereby, to reduce the production and experiment efforts. In this way, it will be possible to direct the further material development. MMC modeling at the macroscale will be provided by means of the finite element method. The effective properties of the single domains representing the microstructure on the microscale will be calculated using the numerical homogenization procedure. The suitable homogenization and mod-eling of the plastic flow in the metal and damage in the ceramics were proposed in the previous phase of this project. For refining these models, specific experimental studies will be performed with regard to the three-dimensionality of the microstructure as well as for the identification of some missing input parameters. The 3D representation of the domains by means of computer tomogra-phy of the ceramic preform will be provided and after that directly utilized for creation of the FE models of the real microstructure and for generation of the 3D synthetic microstructure. These models will be utilized for improvement of the developed homogenization procedure. In the follow-ing, the FE modeling and homogenization will be provided for calculation of the thermal properties of the domains. After the experimental verification of the micro-scale modeling, the developed methods will be used for microstructure optimization on the macroscale. Due to the large difference between the thermal properties of the two phases, the optimization of the heat flow in MMC components is important both theoretically and in relation to problems of the material development. We consider three optimization problems: firstly, the minimization of the highest local temperature (hot spot) for the heat conduction problem; secondly, the minimization of the effective thermal expansion for the thermo-elastic problem; finally, the proposed optimization procedures will be extended for the solution of the multiphysics problem with two weakly-coupled fields (heat conduction and elasticity).

• DFG Programme: Research Grants